This study investigated the changes in fishing capacity of gillnets deployed and abandoned over wrecks and on open ground in UK coastal waters. Divers surveyed 11 wrecks and found the remains of 27 separate gillnets (lost from the fishery) distributed among 7 of the wrecks. No animals (alive or dead) were found entrapped in any of these gillnet remains, whose fishing capacities were estimated to be negligible. Two gillnets were deployed and deliberately abandoned, one over a wreck and another on open ground. They were subsequently monitored for 2 years by divers. Both demonstrated a loss in fishing capacity of more than 50% during the first few weeks of immersion. The open ground net was washed ashore after 58 days, while the wreck net remained in situ and continued to fish, albeit with decreasing capacity, over 2 years. The study supports the general view that lost/abandoned gillnets in UK coastal waters are an insignificant source of unaccounted fishing mortality and do not present an ecological hazard whether deployed over wrecks or on open fishing ground.